JP4056261B2 - Planar carbon segment commutator - Google Patents

Abstract

A planar carbon segment commutator comprises a commutator base 10 of insulating material. The base has a rotational axis and front and rear surfaces, extending, at least in part, transversely to the rotational axis. A plurality of apertures 16 extend through the base. The commutator also comprises a plurality of commutator terminals 20 each of which comprises a terminal portion 21 and a contact portion 22. The contact portion 22 of each terminal extends through a respective aperture 16 and is bent to lie against or in close proximity to the front surface of the base 10. The terminal portion of each terminal has two cutting edges for cutting insulation on a connector portion of a winding and a slot which in use straddles and grips the connector portion. The commutator also comprises a plurality of carbon segments 30 formed on the front surface of the base and over the contact portions 22, respectively, of the terminals 20 and a housing (Figure 9) having a plurality of housing recesses for receiving the terminal portions 21, respectively, of the terminal. <IMAGE>

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a planar carbon segment commutator for use with a brush that supports axially relative to the planar contact surface of the commutator, rather than supporting it radially as in the case of a cylindrical commutator.
[0002]
[Prior art]
Providing a planar commutator with a plurality of commutator terminals attached to the commutator base and overmolded with carbon segments is known, for example, from EP 0583892. However, each of these known planar commutator terminals has a tang, which must be connected to the armature winding of the electric motor.
[0003]
A number of known methods for making such connections are commonly used. When the winding is formed of a low temperature wire, solder and flux methods are usually used. Alternatively, a cold clamp on the stripped wire is used to make the connection. When processing hot wires, heat must be applied and, if possible, flux should be applied to remove the insulating coating from both ends of the wire.
[0004]
[Problems to be solved by the invention]
However, all of the above methods involve a number of inherent problems and undesirable side effects.
Heat causes embrittlement of the copper wires used in most armature windings and promotes rapid oxidation. The use of heat requires a strong structure that supports the commutator to minimize plastic distortion. This requirement calls for the use of high temperature compression grade molding materials. A further common problem is caused by accidental insulation stripping during armature winding, which is often automated. As the wire passes over the commutator metal, damage to the wire insulation can occur and such damage often manifests as a shorted winding. Furthermore, there is always a risk of sagging in the wound wire which causes corrosion due to acceleration due to centrifugal and inertial forces.
[0005]
[Means for Solving the Problems]
According to the present invention, a rotating shaft, a commutator base made of an insulating material having a front surface and a rear surface at least partially extending laterally with respect to the rotating shaft, a plurality of first openings penetrating the commutator base, and a terminal A plurality of commutator terminals each having a portion and a contact portion, and a plurality of carbon segments formed on the front surface of the commutator base above each contact portion of the commutator terminal, and a contact of each commutator terminal The portions are curved so that they pass through the respective first openings of the commutator base and lean against the front surface of the base or are in close proximity, and the terminal portion of each commutator terminal cuts the insulation on the connector portion of the winding A planar carbon segment commutator is provided that has two cutting edges and a slot that grips the connector portion in use.
[0006]
Preferably, the commutator includes a housing having a plurality of housing recesses each receiving a terminal portion.
Preferably, each housing recess has means for positioning each connector portion of the winding relative to each recess, and the commutator base, commutator terminal and housing are translated once with respect to the housing. When the terminal part enters the housing recess, the cutting edge peels off the insulation of the connector part of the winding, and the slot is configured to establish and maintain electrical contact with the connector part of the winding by eliminating insulation .
[0007]
Preferably, the commutator base has a cylindrical skirt for receiving the housing, extending rearward from the rear surface.
Preferably, the front surface of the commutator base has a plurality of recesses, and each contact portion is disposed on each recess and has at least one opening through which each commutator segment is formed. The material extends into the recess to help secure the segment to the terminal.
[0008]
Preferably, the commutator base has a plurality of second openings in communication with the recesses, and the material forming the commutator segments extends through the second openings to assist in securing the segments to the commutator base. .
Preferably, the commutator base has a plurality of third openings through which the material forming the commutator segments extends to assist in securing the commutator segments to the commutator base.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail by way of example with reference to the accompanying drawings.
Referring initially to FIGS. 1 and 2, the commutator base 10 is made of a molding material and has a circular front wall 11 and a cylindrical skirt 12 extending rearwardly from the front wall 11. The base 10 also has a center boss 13, and the base 10 is fitted to an armature shaft (not shown) by the center boss.
[0010]
A plurality of ribs 14 spaced in the circumferential direction and extending in the axial direction are provided on the inner surface of the skirt 12. Its purpose will be described later.
The front wall 11 has a central opening 45 aligned with the boss 13, eight elongated radially extending recesses 15 spaced equiangularly, and an elongated slit-shaped opening 16 aligned radially with each recess 15. .
[0011]
Each recess 15 communicates with the opening 17 at its radially inner end.
Two openings 18 are provided in association with each recess 15, the openings being arranged adjacent to the radially outer end of the recess 15, one on each side of the recess 15.
The front wall 11 also has an outer ring of slots 19 that are angularly spaced.
[0012]
The commutator terminal 20 shown in FIGS. 7 and 8 has a terminal portion 21 and a contact portion 22. The contact portion 22 is in the form of a finger having three openings 23, 24 and 25. The terminal portion 21 is rectangular (as shown in the development) and its short axis coincides with the long axis of the contact portion 22. The terminal portion 21 has a central cutout portion 26 that is symmetrical with respect to both the short axis and the long axis of the terminal portion 21. The width of the cutout portion 26 is reduced toward the two slots 27 at the maximum at the center of the terminal portion 21. Two cutters 28 project into each slot 27 a small distance. These cutters 28 form sharp edges that cut the insulation on the connector portion of the armature winding. The terminal portion 21 also has two hooks 29. The purpose will become clear later.
[0013]
To assemble the terminal 20 to the base 10, the fingers 22 are pushed into the base through each opening 16 and the fingers 22 are then bent to extend radially inward toward the recess 15.
[0014]
A carbon commutator segment 30 is then formed on the front wall 11 of the commutator base 10 above the fingers 22. This may be achieved by hot pressing a disk of raw graphite material onto the front wall 11 and then cutting the disk into eight segments 30. The raw graphite material is a graphite mixture prior to sintering or heat treatment to solidify the binder. During hot pressing, the binder softens (and liquefies if possible), which causes the mixture to flow under pressure through the openings 23, 24 and 25 of the fingers 22 into the recesses 15 and the slots 19, FIG. 6 flows through openings 17 and 18 as shown in greater detail in FIG. The binder is made of a thermosetting material such as a phenolic resin, but once melted or cooled, it becomes heat resistant and forms a stable contact surface for the commutator. As an alternative to hot pressing, an overmolding process can also be used. In the latter process, the components, i.e. commutator base 10 and terminal 20, are placed in a mold, and after the latter process, graphite material is injected into the mold. A hot pressing or forming process forms a good electrical connection with the fingers 22.
[0015]
With reference to FIGS. 9 and 10, a housing 35 for the terminal portion 21 of the terminal 20 is shown. The housing 35 is crown-shaped and includes a central boss 36 for receiving the armature shaft and eight radially outwardly extending housing portions 37 spaced about the circumference of the boss 36. Have The housing part 37 forms a housing recess 38 and is used to make a connection between each part of the armature winding and one of the terminal parts 21 of the terminal 20. Each housing portion 37 has a side wall 39, an end wall 40 and a cover 41. The side wall 39 is parallel to the longitudinal axis of the boss 36.
[0016]
A post 42 projects from the inner surface of the end wall 40 toward the center and extends into the housing portion 37 to approximately half the length of the side wall 39. The support column 42 extends in parallel with the longitudinal axis of the boss and is connected to the housing 35 only by the end wall 40. Each side wall 39 has a slot 43 that extends parallel to the longitudinal axis of the boss 36 by a length from the commutator end of the housing 35 to the height of the free end of the post 42. Part of the armature winding passes through the slot 43 and can be seated on the end of the support column.
[0017]
During assembly of the armature of the electric motor, the housing 35 is disposed on the armature shaft. The lead wire of the armature winding is inserted into one of the housing portions 37 by placing the end of the wire into a slot 43 provided in the side wall 39. The wire is drawn into the housing portion 37 until the wire is seated on the post 42. From here, the first armature coil is wound. At the end of the winding of the first coil, the armature is indexed and the wire is similarly placed in the next housing part 37 without breaking the continuity of the wire. This process is repeated until all the coils have been wound, and the end of the winding is then inserted into the slot 43 of the first housing part 37, adjacent to the tip placed on the post 42 at the beginning of the winding operation. It is pushed in until it does. The wire is then cut and the armature is removed from the winding machine.
[0018]
The housing 35 has a winding portion made of an insulated wire disposed in each housing 37. Each winding portion is in a tensioned state and is tightly pulled with respect to each column 42. The commutator base 10, along with the terminals 20 and commutator segments 30, slides on the armature shaft so that the terminal portions 21 of the terminals enter each housing portion 37 and the housing portions are disposed between the ribs 14. The Each terminal portion 21 approaches the winding portion held in the housing portion 37, and the slot 27 moves along the wire. The cutter 28 cuts the insulation of the wire that is deformed as the slot moves along the wire. This provides intimate contact between the metal and the terminal portion 20. The barbs 29 grip the cover 41 of the housing 35 and thus hold the terminal portion 21 in the housing 35.
[0019]
This method of manufacturing a commutator is itself an automated process. The application of heat is not necessary, thus avoiding the risk of distorting the associated housing. There is no embrittlement of the wound wire and problems associated with oxidation are avoided. The use of flux is denied and there is no chemical reaction or consequential corrosion resulting from the connection. The armature winding can be formed by a single continuous winding, and the possibility of the occurrence of slack due to the cutting of the winding for connection with each coil is avoided.
[Brief description of the drawings]
FIG. 1 is a perspective view from the front side of a commutator base of one embodiment of a planar commutator according to the first aspect of the present invention;
2 is a perspective view from the rear side of the commutator base shown in FIG. 1. FIG.
FIG. 3 is a plan view of the assembled commutator.
FIG. 4 is a bottom view of the assembled commutator.
5 is a cross-sectional view taken along line AA in FIG.
6 is a cross-sectional view taken along line BB in FIG.
FIG. 7 is an enlarged perspective view of a commutator terminal.
FIG. 8 is a development view of the terminals shown in FIG. 7;
FIG. 9 is a perspective view of a terminal housing.
10 is a partial cross-sectional view of a portion of the housing of FIG. 9. FIG.
[Explanation of symbols]
10 commutator base 11 front wall 12 skirt 13 central boss 14 rib 15 recess 16 opening 17 opening 18 opening 19 slot 20 commutator terminal 21 terminal part 22 contact part 23, 24, 25 opening 26 cutout part 27 slot 28 cutter 29 hook 30 Commutator segment 35 Housing 36 Center boss 37 Housing portion 38 Housing recess 39 Side wall 40 End wall 41 Cover 42 Post 43 Slot 45 Center opening

Claims (13)

A commutator base (10) of insulating material having a rotating shaft and a front surface (11) and a rear surface extending at least partially transverse to the rotating shaft;
A plurality of commutator terminals (20) each having a terminal portion (21) and a contact portion (22);
In a planar carbon segment commutator comprising a plurality of carbon commutator segments (30) formed on the front surface (11) of the commutator base (10) above each contact portion (22) of the commutator terminal,
The contact portion (22) of each commutator terminal (20) is curved so as to pass through the respective first opening (16) of the commutator base (10) and lean against the front surface (11) of the base. The terminal portion (21) of each commutator terminal (20) has a cutting edge (28) for cutting the insulation on the connector portion of the winding, and a slot (27) for holding the connector portion across the connector portion in use. have a front of the commutator base (10) (11) has a plurality of recesses (15), each contact portion (22) is disposed on each recess (15) and at least one opening ( 23), and the material forming each commutator segment (30) through the opening extends into the recess (15) to assist in securing the segment (30) to the terminal (20). Planar carbon segment rectification .   The commutator according to claim 1, further comprising a housing (35) having a plurality of housing recesses (38) for receiving the terminal portions (21) of the commutator terminals (20), respectively.   Each housing recess (38) has means (42, 43) for positioning each connector portion of the winding relative to each recess, and commutator base (10), commutator terminal (20) and housing (35). ) When the base (10) translates once relative to the housing (35), the terminal portion (21) enters the housing recess (38) and the cutting edge (28) is insulated from the connector portion of the winding. A commutator according to claim 2, characterized in that the slot (27) is configured to establish and maintain electrical contact with the connector part of the winding by means of insulation removal.   Commutator base (10) according to claim 2 or 3, characterized in that the commutator base (10) has a cylindrical skirt (12) for receiving the housing (35) extending rearward from the rear face. The commutator base (10) has a plurality of second openings (17) respectively communicating with the recesses (15), and a material extending through the second openings to form a commutator segment (30) extends. The commutator according to claim 4 , which assists in fixing the (30) to the commutator base (10). A commutator according to claim 4 or 5 , wherein the recess (15) is elongated and extends in the radial direction of the commutator base (10). The commutator according to any one of claims 4 to 6 , wherein the first openings (16) are each radially aligned with the recesses (15) and arranged outwardly of the recesses (15). The commutator base (10) has a plurality of third openings (18) spaced from the recesses (15), through which the material forming the commutator segments (30) extends. The commutator according to any one of claims 4 to 7 , which assists in fixing the commutator segment (30) to the commutator base (10). 9. A commutator according to claim 8 , wherein two third openings (18) are provided, one on each side of each recess, associated with each one of the recesses (15).   The commutator base (10) has a plurality of third openings (18), and the commutator of the commutator segments (30) extends through the third openings to form a commutator segment (30). The commutator according to any one of claims 1 to 4, which assists in fixing to the base (10). Commutator according to the commutator base (10) is any one of claims 1 to 10 having a central boss having a central opening for receiving the armature shaft (13).   A commutator according to claim 2, wherein the commutator base has a central boss (13) for receiving the armature shaft. The commutator according to claim 12 , wherein the housing (35) also has a central boss (13) and a coaxial central boss (36) of the commutator base (10) for receiving the armature shaft.

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